Block copolymers continue to garner significant interest due to their propensity to form self-assembled nanostructures, the morphologies of which are determined by the mutual compatibility and the volume fractions of the constituent blocks. To use such copolymers to create nanoporous structures, one of the blocks should be selectively degraded after assembly. Techniques to achieve such structures typically involve rather harsh conditions and/or are limited to a few classes of polymers. Recently, a synthetic methodology has been reported in which acid-catalyzed cleavage of PS-PEO block copolymers can be achieved under mild conditions, which has been used subsequently to generate nanoporous thin films. However, the use of such an acid-labile linker moiety is restricted to but a few block copolymers. Further, such an approach does not provide a reactive residual functional group for subsequent chemistry on the resulting nanopore wall.
Various other techniques have been utilized to selectively degrade or remove one of the copolymer blocks. Such techniques include chemical etching, uv-degradation, ozonolysis, and the like. However, such processes tend to be unduly harsh with respect to degradation of either the block structure or resulting terminal group functionality. As a consequence, thin film integrity, or nanopore structure and definition and/or pore wall functionality can be compromised.